For example, a case member for receiving an on-vehicle CCD (Charged Coupled Device) camera unit (which is an electrical part) is required to have a high gas-tight performance (In other words, a high sealing performance) in order to protect the on-vehicle CCD camera unit from foreign matters such as dirt, dust, water and others.
By the way, generally, most of car batteries to be mounted on vehicles such as an automobile have a rated output voltage value of 12V (volt), and also there are other car batteries having a rated output voltage of 24V, 36V or other values.
On the other hand, an internal-operating voltage value of the on-vehicle CCD camera unit is lower (for example, on the order of 3V) than an output voltage value of the car battery, and therefore a DC/DC converter is provided at the on-vehicle CCD camera unit, and a voltage of electric power, supplied from the car battery, is converted into the internal-operating voltage of the on-vehicle CCD camera unit by this DC/DC converter.
A loss, developing in the DC/DC converter of the on-vehicle CCD camera unit during its voltage-converting operation, produces heat which markedly increases the temperature within the case member receiving the on-vehicle CCD camera unit in a sealed condition, and therefore taking a radiating performance into consideration, the case member, made of metal such as aluminum, has been used by choice.
For example, there is known a technique in which an on-vehicle CCD camera unit with a connector portion is incorporated in a case member made of aluminum, and a gap between the connector portion of the on-vehicle CCD camera unit and the case member is sealed by a seal member (rubber plug), thereby sealing the case member (see, for example, Patent Literature 1).
In recent years, the amount of heat generated from a DC/DC converter has been markedly decreased because of an enhanced voltage conversion efficiency, and it has now become unnecessary that a metal-made case member should be used as one for receiving the on-vehicle CCD camera unit provided with such DC/DC converter.
Therefore, for the purpose of achieving a lightweight design and also for cost-reducing and other purposes, there is a technical trend toward the use of a synthetic resin-made case member for receiving an on-vehicle CCD camera unit. In the development of such a synthetic resin-made case member, a study has been made of the integral molding of the case member with a connector having connection terminals for electrical connection to an on-vehicle CCD camera unit received in the case member, and more specifically a study has been made of the formation of the case member, having a connector portion having the connection terminals, by insert molding.
However, even when the insert molding is carried out, microscopic gaps are formed between the connection terminals and the molded resin, and therefore a seal member is provided at the connector portion, having the connection terminals, in intimately-contacting relation to the connection terminals. As one example of a connector employing such a seal member, there is known one in which the sealing is effected by a seal member through which connection terminals extend in intimately-contacting relation thereto (see, for example, Patent Literature 2).
In order to eliminate adverse effects of foreign matters such as dirt, dust, water and others, entering or intruding from the exterior, on a case member for receiving an on-vehicle CCD camera unit in a sealed condition, the case member is required to have such a sealing performance that leakage will not occur even when a pressure, for example, of 400 kPa, is applied thereto.
However, when a pressure is applied to the interior of the case member having the connector portion having the seal member disposed in intimate contact with the connection terminals as described above, there is a possibility that the seal member is pushed out by gas leaking through gaps between the connection terminals and the molded resin, and is displaced toward a mating connector insertion port of the connector portion, so that the sealing performance of the case member is affected.
Also, in the case where in order to obtain a higher sealing performance, a thin, annular lip portion is formed on a seal member, and extends in a direction of connecting of the connector portion to a mating connector in surrounding relation to electrical contact portions of connection terminals, there is a possibility that this annular lip portion is pressed by a front end portion of the mating connector to fall inwardly (that is, toward the connection terminals) into a folded condition during the fitting of the connector portion and the mating connector to each other, so that the mating connector is completely fitted into the connector portion in this condition. There is a high possibility that the desired sealing performance of the case member can not be obtained when such falling of the annular lip portion occurs, and therefore it is necessary to improve this.
Patent Literature 1: JP-A-2002-231375 (Pages 6 to 24, FIG. 1)
Patent Literature 2: JP-A-9-245880 (Pages 3 to 5, FIG. 1)